The present invention relates to an apparatus for sensing a load, and more particularly, to an apparatus for sensing a load imparted to a vehicle seat by a vehicle occupant.
A conventional vehicle occupant load sensing apparatus includes a load sensor placed between a vehicle seat frame and a support mount for the seat. The sensor is directly within the vertical load path of the occupant""s weight and responds to the vertical loads imparted to the seat by the occupant of the seat. Since the seat frame and the support mount must withstand large torque loads (i.e., tilting of the seat frame during crash conditions), typically the sensor also must be constructed to withstand large torque loads. This construction lessens the sensitivity of the sensor in the vertical load path. Thus, the sensor may not produce a reliable vertical load output signal.
A load sensing apparatus, which decouples the torque and vertical loads and also maintains a constant vertical spring rate, would not have to withstand substantial torque loads and thereby may be more likely to produce an accurate occupant load output signal which is consistent for equal upward and downward loads in the vertical load path.
The present invention relates to an apparatus for use in a vehicle having a seat for a vehicle occupant and a vehicle floor pan for supporting the vehicle seat. The apparatus includes a vehicle seat frame for supporting a load of the vehicle occupant in the vehicle seat and a weight sensing mechanism for sensing the load of the vehicle occupant. The weight sensing mechanism includes a parallelogram linkage, a sensor lever, and a sensor. The parallelogram linkage includes a first beam and a second beam that extends parallel to the first beam. The first and second beams each have adjacent interconnected first ends that receive the load of the vehicle occupant. The first and second beams each further have adjacent interconnected second ends. The second ends transmit the load of the vehicle occupant to the vehicle floor pan. The first and second beams each bend in response to the load of the vehicle occupant. The sensor lever is interposed between the first and second beams. The sensor lever has a connection with the first and second beams that causes the sensor lever to deflect upon bending of the first and second beams. The sensor senses the deflection of the sensor lever and provides an output signal indicative of the amount bending of the first and second beams.